This mod adds new blocks, named SafeStone. This mod has two modes, you can configurate to B:invertSpawnRule is true or false.
1st mode (As a default and B:invertSpawnRule = true):
Mobs can’t spawn on SafeStone.
2nd mode (B:invertSpawnRule=false, few older versions are not supported):
Mobs can’t spawn on any blocks like a pieceful mode, but mobs can only spawn on SafeStone.
Place SafeStone on MobSpawner, spawner can’t spawn any mobs (Few older versions are not supported).